Biology subjects

Frank, D. D.

Publications and source records attributed to Frank, D. D..

5 recordsLinked to original sources

bioRxiv2026

Spontaneous neural activity in the developing ant olfactory system

Spontaneous neural activity is a pillar of mammalian neurodevelopment. In mammals, developing olfactory sensory neurons (OSNs) show spontaneous activity patterns that depend on the olfactory receptor (OR) they express. This activity is necessary for proper sorting of OSN axons into olfactory bulb glomeruli. This contrasts with the simpler olfactory system of the fruit fly Drosophila melanogaster, where antennal lobe glomeruli form without functional ORs. Compared to Drosophila, ants have a vastly expanded olfactory system and, unlike Drosophila, require functional ORs for proper development. This raises the possibility that ants, like mammals, rely on spontaneous neural activity. To test whether developing ant OSNs are spontaneously active, we performed live calcium imaging in translucent pupae of the clonal raider ant Ooceraea biroi, using a transgenic line expressing the genetically encoded calcium indicator GCaMP6s in OSNs. Developing O. biroi OSNs exhibit spontaneous calcium transients from the earliest stages of glomerulus formation, and features of this activity change over the course of metamorphosis. During early stages, activity is faster, varies widely between cells, and is uncorrelated across the OSN population. By mid-metamorphosis, activity has slowed, with longer calcium events and fewer peaks per cell. As pupae approach eclosion, a new mode appears, with rhythmic, sawtooth-shaped calcium events that synchronously engage OSNs in both antennae. This stage-dependent spontaneous activity suggests that the expanded ant olfactory system may use a developmental logic more akin to mammals than to Drosophila.

neuroscience↗

bioRxiv2025

FERAL: A Video-Understanding System for Direct Video-to-Behavior Mapping

Quantifying animal behavior often requires segmenting continuous actions into discrete, interpretable states, yet most automated pipelines infer actions from keypoint dynamics and are limited by keypoint tracking quality. Here we present FERAL (Feature Extraction for Recognition of Animal Locomotion), a supervised video-understanding toolkit that maps raw video directly to frame-level behavioral labels, bypassing the keypoint-extraction and pose-classification stages of conventional pipelines. Across benchmarks, FERAL matches or exceeds state-of-the-art pose- and video-based baselines. On the CalMS21 mouse social-interaction benchmark, it exceeds Googles VideoPrism using only a quarter of the training data. FERAL generalizes across species (apes, zebras, mice, ants, flies, and nematodes), recording conditions, and levels of organization, from single animals to social interactions and colony-scale collective behavior. Released as a user-friendly, open-source package, it integrates with existing analysis pipelines. By enabling scalable, species-agnostic behavioral quantification directly from raw video, FERAL broadens the experimental paradigms available for studying animal behavior.

animal behavior and cognition↗

bioRxiv2025

A reference brain for the clonal raider ant

Ants exhibit remarkable collective and social behaviors, such as alloparental care1, chemical communication2, homing3, and cooperative group hygiene4. The clonal raider ant Ooceraea biroi is especially well-suited for investigating the neuronal and genetic underpinnings of these behaviors5. Unlike most ant species, O. biroi lacks a queen caste. Instead, colonies consist entirely of regular workers and slightly larger intercaste workers6. All workers reproduce in synchrony via parthenogenesis, giving rise to age-matched cohorts of clonally identical offspring7,8. This unique life history enables precise experimental control over age, genotype, and colony composition. These features have also facilitated the introduction of genetically encoded calcium indicators into O. biroi, enabling in vivo two-photon imaging to investigate the neural basis of social behaviors9. Despite its promise as a neuroscience model, the structure of the clonal raider ant brain has not been systematically characterized, and a representative reference brain does not exist. To address this gap, we imaged the brains of 40 age-matched, genetically identical individuals with confocal microscopy and, using 3D groupwise registration, generated the first reference brain for the species. We introduce a registration pipeline to align brains to this reference, facilitating the comparison of anatomical features across labeling experiments with high spatial precision. Unexpectedly, despite homogeneity in genotype, age, and external morphology, we discovered extensive interindividual variability across our collection of brain samples. This raises the possibility that behavioral division of labor in O. biroi is linked to individual differences in brain structure. This work provides a powerful resource for the emerging clonal raider ant neuroscience community and reveals novel features of the species neurobiology that may influence social behaviors and colony function.

neuroscience↗

bioRxiv2024

Pheromone representation in the ant antennal lobe changes with age

While the neural basis of age-related decline has been extensively studied (1-3), less is known about changes in neural function during the pre-senescent stages of adulthood. Adult neural plasticity is likely a key factor in social insect age polyethism, where individuals perform different tasks as they age and divide labor in an age-dependent manner (4-9). Primarily, workers transition from nursing to foraging tasks (5, 10), become more aggressive, and more readily display alarm behavior (11-16) as they get older. While it is unknown how these behavioral dynamics are neurally regulated, they could partially be generated by altered salience of behaviorally relevant stimuli (4, 6, 7). Here, we investigated how odor coding in the antennal lobe (AL) changes with age in the context of alarm pheromone communication in the clonal raider ant (Ooceraea biroi) (17). Similar to other social insects (11, 12, 16), older ants responded more rapidly to alarm pheromones, the chemical signals for danger. Using whole-AL calcium imaging (18), we then mapped odor representations for five general odorants and two alarm pheromones in young and old ants. Alarm pheromones were represented sparsely at all ages. However, alarm pheromone responses within individual glomeruli changed with age, either increasing or decreasing. Only two glomeruli became sensitized to alarm pheromones with age, while at the same time becoming desensitized to general odorants. Our results suggest that the heightened response to alarm pheromones in older ants occurs via increased sensitivity in these two core glomeruli, illustrating the importance of sensory modulation in social insect division of labor and age-associated behavioral plasticity.

neuroscience↗

bioRxiv2023

Rapid threat assessment in the Drosophila thermosensory system

Neurons that participate in sensory processing often display "ON" responses, i.e. fire transiently at the onset of a stimulus. ON transients are widespread, perhaps universal to sensory coding, yet their function is not always well-understood. Here, we show that ON responses in the Drosophila thermosensory system extrapolate the trajectory of temperature change, priming escape behavior if unsafe thermal conditions are imminent. First, we show that second-order thermosensory projection neurons (TPN-IIIs) and their Lateral Horn targets (TLHONs), display ON responses to thermal stimuli, independent of direction of change (heating or cooling) and of absolute temperature. Instead, they track the rate of temperature change, with TLHONs firing exclusively to rapid changes (>0.2{degrees}C/sec). Next, we use connectomics to track TLHONs output to descending neurons that control walking and escape, and modeling and genetic silencing to demonstrate how ON transients can flexibly amplify aversive responses to small thermal change. Our results suggest that, across sensory systems, ON transients may represent a general mechanism to systematically anticipate and respond to salient or dangerous conditions.

neuroscience↗